(1) Field of the Invention
This invention relates to a molding machine which can continuously perform the operation from injection molding of a preform to stretching blow molding of a synthetic resin molded article such as a bottle or a container.
(2) Description of Prior Art
A molding machine of this kind is generally known from U.S. Pat. No. 4,105,391. This molding machine has been developed by the present inventor, in which a lower base on a bed and an upper base thereabove are connected together by a tie rod at the peripheral portions, and between these two bases operations such as injection molding of a preform, temperature control, stretching blow molding and removal of a molded article may be carried out successively.
The aforesaid machine is also designed so that devices for an injection core and a blow core and drive devices are mounted on the upper base, a rotary disc having a neck mold at the lower side thereof is provided on the underside of the upper base, and a preform injection molded into the neck mold and a stretching blow molded article may be transferred by the rotary disc.
Such a molding machine as described has the disadvantages that since in this machine, the lower base and the upper base are in the locked state, a spacing between both the bases cannot be varied according to a dimension of height of the molded article; even if the spacing has an allowance, the dimension of height is subjected to molding limit, lacking in general-purpose use; and in addition, in molding small bottles, injection and blow cavities have to be raised every time.
In addition, it is necessary that the injection cavity side is moved up and down with respect to the neck mold on the upper base side to open and close the mold, and therefore the injection apparatus cannot be always placed in nozzle touch with the injection cavity and a hot runner block, because of which means for nozzle touch operation every opening and closing and for prevention of leakage of resins from the nozzles are required.
Furthermore, there are disadvantages in that clamping devices have to be provided on both the injection cavity and injection core, and since the injection cavity is connected to the upper end of the clamping rod, a side run-out occurs in the injection cavity during closing due to the side pressure during the nozzle touching, causing the preform to be one-sided in wall thickness.
Moreover, there poses various problems in that in the transfer accomplished by the rotary disc, the preform and the molded article depict a circular locus whereas the mold cavity is provided on the lower base parallel to the tangential line of the circular locus and to be opened and closed in a radial direction, and therefore, the molded article becomes impinged upon the end of the blow cavity and damaged during rotation and transfer thereof unless opening extremely greater than a diameter of the molded article is carried out.